/* 字符串的扩展方法 */
// includes();
// const name = 'glh';
// const message = `Error: foo is not defined: ${name}`;
// console.log(message.startsWith('E'));
// console.log(message.endsWith('ned'));
// console.log(message.includes('glh'));

// const mySymbol = Symbol();
// const a = {};
// a.mySymbol = 'Hello!';
// console.log(a[mySymbol]); //undefined
// console.log(a['mySymbol']); //hello
